This invention relates to pen based computer systems and in particular to a pen based edit correction interface method and apparatus which uses handwritten symbols to delete, rearrange or modify existing text.
Pen based computer systems are becoming increasingly popular. Pen-based systems allow the user to easily use a computer without first learning to keyboard. In addition, continuous speech recognition systems are also becoming increasingly popular. Speech recognition systems allow a user to dictate directly into their computer. As the accuracy and speed of each of these systems increases the appeal to a general computer user increases.
It is generally recognised that in order to obtain acceptance in the marketplace these systems need to resemble existing practices as much as possible. Accordingly, the computer system developers are trying to develop systems that are modelled on existing practice. However, there are still problems with regard to speed, accuracy and ease of use when considering many of these systems.
Before considering some of the existing systems it is important to define some common terminology used in association with computer based systems in general and pen based systems in particular. Specifically a Digitizer is an Electromagnetic Tablet capable of receiving radio frequency signals from the tip of an Electronic Pen. Note that Software Drivers provided with the Tablet when installed, are capable of determining the (X,Y) coordinate position of the tip of the Electronic Pen on the Tablet, by analysing the signals received by the Tablet from the tip of the Electronic Pen. Proximity sensing refers to the ability of an Electromagnetic Tablet to sense the position of the tip of the Electronic Pen that is within a given distance of the planar surface of the Tablet. A pointer is a visual icon displayed on the computer screen to indicate the absolute or relative (X,Y) coordinate position of the tip of the Electronic Pen with respect to the planar surface of the Digitizer. Typically, the shape of the pointer is used to indicate whether the Electronic Pen is in selecting or writing mode. The pointer is in selecting mode (ie: user can select a block of text) if it is shaped like an arrow. The pointer is in writing mode (ie: user can generate Electronic Ink) if it is shaped like a pen.
The movement of the Electronic Pen relative to the Digitizer determines the information that is processed. A pen down incident is equivalent to pressing down (but not releasing) the left button on a computer mouse device. A pen up incident is equivalent to releasing the left button on a computer mouse device (after it has been pressed down). A single-click or tap is a pen down followed by a pen up within a pre-selected interval of time, where the absolute distance between the initial pen down coordinate and all subsequent present pen down coordinates stays within a stroke tolerance value. A double-click consists of two consecutive single-clicks, where the absolute distance between the (X,Y) pen up coordinate of the first single-click and the initial pen down coordinate of the second single-click falls within a double click tolerance value and the pen down event of the second single click follows the pen up event of the first single-click within a pre-selected interval of time.
A point is defined as (X,Y) coordinate which represents the absolute position of the tip of the Electronic Pen during a pen down event at a given instance of time. A stroke consists of a set of ordered points generated by a pen down event followed by a pen up event, where the absolute distance between the initial pen down coordinate and one or more of the subsequent present pen down coordinates is greater than a pre-set tolerance value within a pre-selected interval of time. Electronic Ink is used to describe the process of displaying one or more strokes on the computer screen by connecting the points which represent the strokes with solid visible line(s). Note that Electronic Ink is only displayed, after the absolute distance between the initial pen down coordinate and one or more of the subsequent present pen down coordinates becomes greater than a pre-set tolerance value within a pre-selected interval of time. ASCII is the American Standard Code of Information Interchange.
Handwriting time-out refers to a logic sequence wherein after each stroke is completed (ie: the user pens up after drawing the stroke) a timer is activated: IF xe2x80x9ca pre-set interval of time elapses before the user pens-down to draw the next strokexe2x80x9d; THEN xe2x80x9call ordered set of strokes (displayed on the computer screen as Electronic Ink) are recognized by handwriting recognition software as ASCII, the timer is de-activated and reset back to zero and all Electronic Ink is erased from the computer screenxe2x80x9d ELSE xe2x80x9cthe timer is de-activated and reset back to zero and all Electronic Ink continues to be displayed on the computer screenxe2x80x9d.
Handwriting recognition is the process of interpreting handwritten symbols based upon the context of the Window with Focus. Handwriting recognition systems have a terminology to describe the symbols used therein. Particularly, shape of a symbol refers to the geometric shape of a symbol (eg: the letter o has a circular shape). The orientation of a symbol refers to the way in which the symbol was drawn. For example, a circle can be drawn either clockwise or counter-clockwise in direction. The way in which a circle is drawn does not affect its geometric shape, however the orientation of a circle drawn clockwise is fundamentally different from the orientation of a circle drawn counter-clockwise. Context refers to one or more sets of pre-defined symbols (eg: digits, letters, punctuation, edit symbols, etc . . . ) that can be recognized within a given Window. Note that typically each Window has only one unique context associated with it at a time. The Window with Focus is the Window that is designated for receiving input (eg: The Window with Focus is usually indicated by the insertion point). The insertion point is the location where text will be inserted into the Window with Focus, usually indicated by a flashing cursor, Edit Symbols are symbols which represent an action (eg: Cut, Copy, Paste, Delete, etc . . . ) executed after Handwriting Recognition Software interprets the symbol.
Theoretically, the greater the number of symbols in a given context the greater the chance that any individual symbol will be mis-interpreted. Further, the greater the number of symbols in a given context that are similar in orientation and/or shape, the greater the probability that similarly orientated and/or shaped symbols will be mis-interpreted for one another. Therefore a number of methods have been suggested to overcome some of the problems associated with accuracy. One method that has been suggested to overcome some of these problems is to provide a palette of buttons for Punctuation Symbols, wherein each button represents a Punctuation Symbol. Another method that has been suggested is a drop down menu. There are inherent problems or inefficiencies associated with each of these methods which will be described in more detail below.
The present invention is directed to a correction method for use with a pen based computer system. The correction method includes the steps of receiving a insertion point coordinate; receiving an inital pen down coordinate corresponding to an initial pen down; receiving a present pen down coordinate corresponding to a present position of a pen; receiving a pen up coordinate corresponding to a pen up; defining an ordered set of points between and including the initial pen down coordinate and the pen up coordinate; determining a first time interval between the pen up and the initial pen down; determining a second time interval between the initial pen down and the present pen down; determining if the relative position of at least two of the initial pen down coordinate, the present pen down coordinate, the pen up coordinate, the first time interval, the second time interval and the ordered set of points corresponds to a set of pre-selected parameters which correspond to activation of one or a plurality of modes; and activating the mode. The different modes include input mode, punctuation mode, correction mode, edit mode and selection mode. A stroke or path drawn in a mode will be compared with a preselected groups of characters used in association with that mode. By dividing functions into different modes the reliability of recognition of the stroke will be increased.
Further features of the invention will be described or will become apparent in the course of the following detailed description.